Node Line Reader (Stream for large files)

lineReader.js

'use strict';
function lineReader(fileName){
	var EM = require("events").EventEmitter,
		ev = new EM(),
		stream = require("fs").createReadStream(fileName),
		remainder = null;

	stream.on("data",function(data){
		if(remainder !== null){//append newly received data chunk
			var tmp = new Buffer(remainder.length+data.length);
			remainder.copy(tmp);
			data.copy(tmp,remainder.length);
			data = tmp;
		}

		var start = 0;
		for(var i=0; i<data.length; i++){
			if(data[i] == 10){ //\n new line
				var line = data.slice(start,i);
				ev.emit("line", line);
				start = i+1;
			}
		}
		if(start<data.length){
			remainder = data.slice(start);
		}else{
			remainder = null;
		}
	});

	stream.on("end",function(){
		if( null!== remainder) {
			ev.emit("line",remainder);
		}
	});

	stream.on('error',function(e){
		console.log(e);
	});

	return ev;
}

module.exports = lineReader;